During his first visit to Mexico, President Obama pledged to do more to keep U.S. guns out of the hands of murderous drug cartels. One promise: to seek approval of a long-stalled treaty against illegal weapons sales.

“I am urging the Senate in the United States to ratify an inter-American treaty known as CIFTA, to curb small-arms trafficking that is a source of so many of the weapons used in this drug war,” the president said at the April 2009 news conference.

To the Mexicans, that might have seemed an easy lift. The U.S. government already complies with the treaty’s provisions. No U.S. laws would have to change, officials say. And some phrases in the treaty had been proposed by the National Rifle Association.

But the symbolically important treaty has gone nowhere, offering a lesson in the political sensitivities of taking even modest legal steps to crack down on gun-smuggling to Mexico. While the Obama administration has taken other actions, such as sending anti-trafficking teams to the border, neither the White House nor Congress has pushed the treaty, which the gun lobby opposes.

President Obama will announce in a visit here today that he will push the U.S. Senate to ratify an inter-American arms trafficking treaty designed to curb the flow of guns and ammunition to drug cartels and other armed groups in the hemisphere.

Senior administration officials confirmed that he will make the announcement after meeting with Mexican President Felipe Calderon this afternoon.

The Obama administration’s commitment to seek ratification [of the treaty] is important because stemming the number of illegal firearms which flow into Latin America and the Caribbean is a high priority for the region and addresses a key hemispheric concern relating to people’s personal security and well-being,” said a senior Obama administration official.

The brutal murder of retired Mexican army Gen. Mauro Tello in Cancun earlier this month was a stark reminder of the wave of drug-related violence that is tormenting Mexico and that threatens to spill over into the United States.

The escalating violence unleashed by Mexico´s drug cartels as they struggle to control trafficking routes and expand their illegal business left 5,700 dead in 2008, with homicide rates spiraling out of control in cities along the U.S. border.

Illegal trafficking of arms from the U.S. helps fuel drug violence. While there are variables in Mexico´s struggle against narcotics-related violence over which the U.S. has little input – such as corruption among the police – working to stem the illegal flow of weapons is something Washington can do. There is a key mechanism in place for doing so; namely, an international convention signed by the U.S. more than 10 years ago but never ratified by the Senate.

This convention, known by its acronym as CIFTA (Inter-American Convention against the Illicit Manufacturing of and Trafficking in Firearms, Ammunition, Explosives and other Related Material), calls for cooperation among members of the Organization of American States (OAS) to control illegal weapons.